ARM: dts: omap4-duovero: Add pdmclk binding for audio

The twl6040 codec is generating the pdmclk, which is used by the McPDM as
functional clock.
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/boot/dts/omap4-duovero.dtsi

@@ -177,6 +177,7 @@ twl: twl@48 {
 
 	twl6040: twl@4b {
 		compatible = "ti,twl6040";
+		#clock-cells = <0>;
 		reg = <0x4b>;
 		interrupts = <GIC_SPI 119 IRQ_TYPE_LEVEL_HIGH>;		/* IRQ_SYS_2N cascaded to gic */
 		ti,audpwron-gpio = <&gpio6 0 GPIO_ACTIVE_HIGH>;		/* gpio_160 */
@@ -207,6 +208,10 @@ &mcbsp1 {
 &mcpdm {
 	pinctrl-names = "default";
 	pinctrl-0 = <&mcpdm_pins>;
+
+	clocks = <&twl6040>;
+	clock-names = "pdmclk";
+
 	status = "okay";
 };